Definition: In this task, you are given an input list A comprising of numbers and alphabets. You need to extract and sort the unique alphabets in the list. The alphabets in the input list will only be in lowercase. Return -1 if there is no alphabet in the input list.
Input: ['m', 's', 'y', '2615', '2327', '7093', '4577', 'l', 'r']

l, m, r, s, y